Autism and immigration background, insights from a population-based study

To examine the relationship between immigration and autism in Manitoba, Canada, using population-based data.

We linked Manitoba's Rehabilitation Centre for Children clinical registry (May 2016-December 2022), the province's primary and only publicly funded autism evaluation site for children ≤6 years, with an official immigration registry. We estimated incidence of autism and adjusted relative risks (aRR) with 95% confidence intervals (CI) across subgroups defined by child and parent immigration status.

A total of 217,811 children aged 18 months to 6 years resided in Manitoba during the study period and met inclusion criteria. Among 2408 children diagnosed with autism, 1136 (47%) had at least one immigrant parent. Compared with Canadian-born children of nonimmigrant parents, autism risk was highest among Canadian-born children of at least one immigrant parent (aRR: 2.29; 95% CI: 2.09-2.51), followed by immigrant children of at least one immigrant parent (aRR: 1.72; 95% CI: 1.42-2.09). Maternal length of stay in Canada and refugee status was not associated with autism risk. In secondary analysis examining parental contribution to likelihood of autism, compared with Canadian children of two nonimmigrant parents, likelihood of autism diagnosis was higher among children in all parental immigration categories, but highest when both the mother and the father were immigrants (aRR: 3.08, 95% CI: 2.62-3.62).

Children of immigrant families in Manitoba had higher rates of autism. Additional studies are warranted to assess whether similar results occur in other Canadian jurisdictions, and to investigate possible underlying factors behind this association.